JPH05119585A - Corona discharger - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the amount of harmful products such as ozone in a corona discharge device used in an electrophotographic device, etc., and improve maintainability, safety, and cost reduction. [Structure] An inner wall surface of a conductive shield member main body 2 in a corona discharge device is covered with an ozone decomposition promoting layer 4. The ozone decomposition promoting layer 4 contains at least one powdery ozone decomposition promoter selected from metal oxides and metals. In the ozone decomposition promoting layer 4, the ozone decomposition promoter is bound to the conductive shield with either the conductive resin composition or the conductive rubber composition, and the ozone decomposition promoter is exposed on the surface. preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona discharge device in an electrophotographic device or the like, and more particularly to a shield member used in the corona discharge device.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as an electrophotographic copying machine, a corona discharge device has been used to charge a photosensitive drum and transfer a toner image formed on the photosensitive drum onto a transfer paper. Has been. As a corona discharge device, for example, there is one provided with a conductive shield 11 formed in an elongated box shape having a U-shaped cross section as shown in FIG.
The shield is made of a metal material such as aluminum or stainless steel, and the discharge wire 12 is stretched between discharge wire fixing members (not shown) made of an insulating material and attached to both ends of the shield. .. A high voltage (DC-5 to DC-5) is applied to the discharge wire 12 by the power supply 13.
-8 KV), a corona discharge is generated between the discharge wire 12 and the conductive shield 11, and the photoconductor 14 is caused by the ions generated by the corona discharge.
The charge on the photoconductor or the toner particles of the dielectric is controlled by charging the transfer sheet to the upper side or charging the transfer sheet.

Although these charging processes have the advantages that they are simple in construction and relatively stable charging performance can be obtained, it is known that harmful substances such as ozone (O ₃ ) are generated. This product is harmful to the human body and is a problem faced by electrophotographic copying machines and the like. Not only that, this product deteriorates the surface of the photoconductor, causing image blurring and deterioration.

Therefore, as a means for removing and reducing harmful products such as ozone discharged from an electrophotographic copying machine, for example, in a general electrophotographic copying machine, heating is performed to fix a toner image on a transfer sheet. A roller system is used, and in order to cool the heat generated there, the air around it is discharged to the outside of the system by a cooling fan.

Further, in Japanese Patent Laid-Open No. 2-273764, a filter having activated carbon or a powder of activated carbon on which a catalyst, for example, a metal oxide containing manganese dioxide as a main component is carried is arranged in the vicinity of the exhaust port. A method of adsorbing or decomposing ozone has been proposed.

Further, in the corona discharge device disclosed in Japanese Patent Laid-Open No. 2-259673, the conductive shield is composed of an activated carbon sheet, and the sheet carries a powdery metal oxide (manganese dioxide). Then, a method of adsorbing or decomposing ozone on the surface of the conductive shield to reduce the ozone concentration is used.

[0007]

However, the above-mentioned prior art has the following problems. First,
When a filter for adsorbing or decomposing harmful products such as ozone is installed in the exhaust opening of devices such as electrophotographic copying machines, the concentration of harmful products such as ozone discharged to the outside of the system of the device. However, there is a problem that these densities cannot be reduced in the vicinity of the photosensitive drum.

Further, when an activated carbon sheet is used for the conductive shield, there is a problem in that maintenance and inspection are troublesome when the effect of adsorption or decomposition of ozone and the like decreases due to the life of the activated carbon sheet.

The present invention is intended to solve the problems of the prior art as described above, and reduces the amount of harmful products such as ozone, and is excellent in maintainability, safety and cost, and corona discharge. The purpose is to provide a device.

[0010]

As a result of intensive studies to achieve the above object, the present inventor has found that the constituent members of a corona discharge device used in an image forming apparatus such as an electrophotographic copying machine Carrying an ozone decomposition promoting layer containing at least one powdery ozone decomposition promoter selected from metal oxides such as manganese dioxide, lead dioxide and platinum and metals on at least the inner peripheral surface of a conductive shield. In particular, by bonding the ozone decomposition accelerator to the conductive shield with the conductive resin composition or the conductive rubber composition and exposing the particles of the ozone decomposition accelerator to the surface, the corona discharge device can be used for a long period of time. It has been found that both functions such as the function as a charging device and the reduction of the amount of generated ozone can be maintained.

That is, according to the present invention, in a corona discharge device comprising a discharge electrode for discharging and a conductive shield surrounding the discharge electrode, an ozone decomposition promoting layer is carried on at least the inner wall surface of the conductive shield. A corona discharge device is provided. Further, according to the present invention, in the above configuration, a corona discharge device characterized in that the ozone decomposition promoting layer contains at least one or more powdery ozone decomposition promoter selected from metal oxides and metals. Provided. Further according to the invention,
In the above structure, the ozone decomposition accelerator in the ozone decomposition promoting layer is bound to the conductive shield by either the conductive resin composition or the conductive rubber composition, and the ozone decomposition accelerator is exposed on the surface. A corona discharge device is provided.

The present invention will be described in detail below with reference to the drawings. Figure 1
FIG. 1 is a cross-sectional view showing a conductive shield member in a corona discharge device according to a configuration example of the present invention, in which 1 is a conductive shield member, 2 is a conductive shield member main body, 3 is a discharge wire, and 4 is ozone decomposition. It is a promotion layer. In the conductive shield member 1 of this configuration example, the inner wall surface of the main body 2 is covered with the ozone decomposition promoting layer 4. That is, as illustrated in detail in an enlarged manner in FIG. 2, the ozone decomposition accelerator 6 is carried on the conductive shield member main body 2 by the conductive binder 5.

By applying a high voltage to the discharge wire 3, the conductive shield member 1 forms an electric field between the conductive shield member 1 and the discharge wire 3 to generate corona discharge. Therefore, the characteristics required of the shield member are that they are electrically conductive in order to enable the formation of an electric field, and that the distance between the discharge wire 3 and the surface of the photoconductor (in the case of an electrophotographic copying machine). Shape retention is required to keep the axes parallel so that they are constant. Therefore, as the constituent material of the shield member main body 2, aluminum, stainless steel, iron having its surface plated, or the like is preferably used.

It is known that ozone is gradually decomposed into oxygen at room temperature, and that decomposition is promoted by metal oxides and metals such as manganese dioxide, lead dioxide and platinum powder. According to the present invention, by supporting the ozone decomposition promoting layer 4 containing the ozone decomposition promoter composed of the metal oxide or the metal powder on the surface of the conductive shield member main body 2, corona discharge is generated in the vicinity of the discharge wire 3. Ozone generated upon initiation is reduced on the inner surface of the shield member main body 2 having a U-shaped cross section. The particle size of the ozone decomposition accelerator used is preferably 10 to 200 μm, and the film thickness of the ozone decomposition promoter layer 4 is suitably about 50 to 500 μm.

The ozone decomposition promoting layer 4 is provided on the shield member main body 2
The binder 5 when supported on the substrate should be electrically conductive and flame-resistant in terms of safety in order to prevent the formation of an electric field between the discharge wire 3 and the shield member body 2. is necessary. Further, a composition having excellent ozone resistance is required because the carried ozone decomposition promoting layer 4 does not fall off the shield member main body 2 for a long period of time.

In order to effectively promote the ozone decomposition, it is necessary to carry the ozone decomposition accelerator particles on the surface of the shield member main body 2 so that the particles are exposed on the surface.
As a method thereof, for example, after applying the binder 5 made of a conductive resin composition or a conductive rubber composition on the surface of the shield member main body 2 and before the binder is cured, a part of the ozone decomposition accelerator particles It is possible to use a method of curing by embedding.

As the binder 5 when the ozone decomposition accelerator is carried on the shield member main body 2, a thermoplastic elastomer (styrene series, olefin series, urethane series, polyester series, polyamide series, 1,2-polybutadiene series, Vinyl chloride type, fluorine type, etc., solvent soluble fluorine resin, room temperature curing type silicone rubber, liquid silicone rubber, chlorosulfonated ethylene rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber, etc., and conductive particles such as carbon black and metal fine particles. A dispersed composition can be used.

[0018]

EXAMPLES Next, the corona discharge device of the present invention will be described in detail with reference to examples.

Example 1 100 parts of a solvent-soluble fluororesin (trade name: Lumiflon LF-601C (manufactured by Asahi Glass Co., Ltd.)) as a conductive binder for supporting an ozone decomposition accelerator on the body of the conductive shield member, 15 parts of carbon black (trade name: Vulcan XC-72 (manufactured by Cabot)) and 100 parts of toluene as a solvent were dispersed for 8 hours in a ball mill disperser to prepare a fluororesin solution containing carbon black. To 100 parts of this resin solution, 10 parts of an isocyanate curing agent (trade name: Coronate HX (manufactured by Nippon Polyurethane Co.)) was added to prepare a conductive paint.

Next, the above conductive paint is applied to the inner wall surface of the shield member body made of aluminum, manganese dioxide particles are attached to the applied surface before the paint is hardened, and the paint film is hardened at 60 ° C. for 1 hour. It was After curing, extra manganese dioxide particles attached to the coated surface were removed.

As described above, a conductive shield member having an ozone decomposition accelerating layer supported by a conductive binder with the particles of manganese dioxide exposed on the surface of the aluminum shield member body was produced. Incidentally, the electric resistance of the conductive binder after curing was 130 Ω · cm ² .

A corona discharge device is constructed by using the conductive shield member obtained as described above, and the corona discharge device is mounted on a laser beam printer LP1060V manufactured by Ricoh Co. Was measured for ozone concentration. The result is shown as a curve A in FIG. In addition to manganese dioxide, lead dioxide and platinum powder can be applied as the ozone decomposition accelerator used in the ozone decomposition promoting layer. The results when these are used are also shown in FIG. Curve B in the figure is for lead dioxide, and curve C is for platinum. The ozone concentration meter is Dasibi Ozon Monito manufactured by Dylec
r Model DY-1500 was used.

Example 2 As a conductive binder, liquid silicone rubber (trade name: S
Before mixing the E6750 (Toray Dow Corning Silicone Co., Ltd.) solution A and solution B mixed at a mixing ratio of 1: 1 and applying this to the inner wall surface of the aluminum shield member body, and before the coating hardens Particles of manganese dioxide and lead dioxide with a mixing ratio of 1: 1 are adhered to the coated surface at 100 ° C,
The coating was cured in 1 hour. After the curing, the extra mixed particles of manganese dioxide and lead dioxide attached to the coated surface were removed.

As described above, the mixing ratio of manganese dioxide and lead dioxide on the aluminum shield member main body is 1:
A conductive shield member having an ozone decomposition accelerating layer supported by a conductive binder with the particles of No. 1 exposed on the surface was prepared. A corona discharge device is constructed using this,
The evaluation was performed in the same manner as in Example 1. The result is shown as a curve D in FIG.

Comparative Example A corona discharge device using only an aluminum shield (without an ozone decomposition accelerating layer) as a conductive shield was mounted on the printer and evaluated in the same manner as in Example 1. The result is shown as a curve E in FIG.

As is apparent from FIG. 3, according to the embodiment of the present invention, the ozone decomposition promoting layer is carried on the inner wall surface of the conductive shield member main body which is a source of ozone, and the ozone is generated by corona discharge. Immediate contact of ozone with the ozonolysis promoter exposed on the surface could significantly enhance the decomposition efficiency.

[0027]

According to the present invention, because of the above-mentioned constitution, the following remarkable effects can be obtained. (1) The ozone decomposition promoting layer (ozone decomposition promoting agent) carried on the shield makes it possible to efficiently reduce the discharge products. (2) It is possible to reduce the cost by simplifying the filter provided in the portion that discharges air containing ozone from an electrophotographic copying machine or the like. (3) Even if an ozone decomposition accelerator is carried on the conductive shield, it is possible to uniformly charge the photosensitive drum and maintain the image uniformity while satisfying the predetermined charging characteristics as the shield. .. (4) It is possible to provide a corona discharge device including a conductive shield member which is excellent in maintainability, safety and cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conductive shield member in a corona discharge device according to a configuration example of the present invention.

FIG. 2 is an enlarged schematic view showing how an ozone decomposition accelerator is carried on a conductive shield member main body.

FIG. 3 shows measurement results of ozone concentration in Examples and Comparative Examples.

FIG. 4 is a cross-sectional view showing a conductive shield member in a conventional corona discharge device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive shield member 2 Conductive shield member main body 3 Discharge wire 4 Ozone decomposition promotion layer 5 Conductive binder 6 Ozone decomposition promoter

Claims (3)

[Claims] 1. A corona discharge device comprising a discharge electrode for discharging and a conductive shield surrounding the discharge electrode, wherein an ozone decomposition promoting layer is carried on at least an inner wall surface of the conductive shield. And corona discharge device. 2. The corona discharge device according to claim 1, wherein the ozone decomposition promoting layer contains at least one kind of powdery ozone decomposition promoting agent selected from metal oxides and metals. 3. The ozone decomposition promoting layer has an ozone decomposition promoting agent bound to a conductive shield with either a conductive resin composition or a conductive rubber composition, and the ozone decomposition promoting agent is exposed on the surface. The corona discharge device according to claim 1 or 2, characterized in that.